Accumulator membrane unit, method for production thereof and rock drilling machine including such an accumulator membrane unit

1. Accumulator membrane unit for inclusion into an accumulator chamber in an accumulator for storing hydraulic energy under pressure, wherein

the accumulator membrane unit includes membrane elements that are sealingly joined at their peripheries and limit an inside membrane volume which varies in dependence of a pressure at an outside of the accumulator membrane unit, and

wherein the accumulator membrane elements are formed from at least one material arranged so that the membrane elements are elastically deformable during pressurizing with an increased hydraulic pressure of the accumulator membrane elements, wherein hydraulic energy is storable as elastic deformation energy in the membrane material itself of the membrane elements.

2. Accumulator membrane unit according to claim 1 ,

wherein the membrane elements are made of a rigid but elastically deformable material.

3. Accumulator membrane unit according to claim 1 , wherein

the accumulator membrane unit forms a convex body in a non pressurized state.

4. Accumulator membrane unit according to claim 3 ,

wherein the membrane elements have a vaulted shape such that the accumulator membrane unit is lens shaped in non pressurized state.

5. Accumulator for storing a hydraulic medium under pressure including a housing with a sealed connection for said hydraulic medium, wherein at least one accumulator membrane unit according to claim 1 is included inside the housing, and wherein the connection for hydraulic medium communicates with a space in an accumulator chamber inside the housing, which space is outside a membrane volume for each at least one accumulator membrane unit.

6. Accumulator according to claim 5 , wherein it is provided with a positioning device for said at least one accumulator membrane unit.

7. Accumulator according to claim 6 , wherein the positioning device includes clamping rings having axial and radial directions for holding the respective accumulator membrane unit in respect of the housing and at occasions relative to sideward positioned accumulator membrane unit(s).

8. Accumulator according to claim 7 , wherein said clamping rings are provided with axially directed recesses for cooperation with a peripheral region of each accumulator membrane unit.

9. Accumulator according to claim 7 , wherein said clamping rings are provided with at least one radial passage for hydraulic medium.

10. Accumulator according to claim 5 , wherein inside one and the same accumulator a plurality of accumulator units having different working points and operating ranges are arranged such that with one and the same accumulator a plurality of working points and operating ranges are realized.

11. Accumulator according to claim 5 , wherein the accumulator membrane unit limits a membrane volume which communicates with the outside of the accumulator.

12. Method for manufacturing an accumulator membrane unit for positioning inside an accumulator chamber in an accumulator for storing energy by means of hydraulic medium under pressure, wherein the accumulator membrane unit includes membrane elements that are joined together at their peripheries, and limit a membrane volume which is variable depending on a surrounding pressure,

wherein

membrane elements are joined together for forming an accumulator membrane unit, which in unpressurized state is convex,

wherein the accumulator membrane elements are formed from at least one material arranged so that the membrane elements are elastically deformable during pressurizing with an increased hydraulic pressure of the accumulator membrane elements,

and wherein the membrane material of the membrane elements is chosen such that hydraulic energy is storable as elastic deformation energy in the membrane material itself.

13. Method according to claim 12 , wherein the membrane elements are joined together through any one from the group: welding, soldering, clamping with intermediate sealing, gluing.

14. Method according to claim 13 , wherein the membrane elements are joined together through welding, and

wherein a radially outwardly directed weld joint is applied surrounding the accumulator membrane elements for joining the membrane elements.

15. Method according to claim 12 ,

wherein two membrane elements that are vaulted in unpressurized state are positioned for forming a lens-shape,

wherein the membrane elements are compressed by a pressing device to an essentially flat state, and

wherein the membrane elements are joined together in this pressed together state.

16. Rock drilling machine including at least one accumulator according to claim 5 .

17. Accumulator membrane unit according to claim 2 ,

wherein the accumulator membrane unit forms a convex body in a non pressurized state.

18. Accumulator for storing a hydraulic medium under pressure including a housing with a sealed connection for said hydraulic medium, wherein at least one accumulator membrane unit according to claim 2 is included inside the housing, and wherein the connection for hydraulic medium communicates with a space in an accumulator chamber inside the housing, which space is outside a membrane volume for each at least one accumulator membrane unit.

19. Accumulator according to claim 8 , wherein said clamping rings are provided with at least one radial passage for hydraulic medium.

20. Method according to claim 13 ,

wherein two membrane elements that are vaulted in unpressurized state are positioned for forming a lens-shape,

wherein the membrane elements are compressed by a pressing device to an essentially flat state, and

wherein the membrane elements are joined together in this pressed together state.